DNase1 exon2 analysis in Tunisian patients with rheumatoid arthritis, systemic lupus erythematosus and Sjögren syndrome and healthy subjects.

Autoimmune diseases (AID) are caused by the loss of immunological tolerance against self-antigens. The deoxyribonuclease I (DNASE1) gene seems to participate in the genetic susceptibility of some AID. In fact, two mutations were reported among systemic lupus erythematosus (SLE) patients from Japan and Spain (the 172 A → T mutation (K5X) and the 46_72 deletion, respectively). The aim of our work was to evaluate the DNASE1 contribution in the genetic susceptibility of rheumatoid arthritis (RA, n = 151), Sjögren syndrome (SS, n = 55) and SLE (n = 34) in Tunisia. DNA from patients and healthy subjects (n = 232) were explored. Both reported mutations were absent among patient and control subjects. The DNASE1 exon2 sequence was analysed among 26 control subjects to identify new polymorphic variations that are possible. Five known SNPs were explored. The G/T transversion (rs8176927: R2S) was the most polymorphic functional nonsynonymous SNP. Using PCR-RFLP method, all DNAs were genotyped for rs8176927 for a case-control design. The statistical analysis showed no significant differences between patients and controls genotype data. In conclusion, our study showed, on the one hand, the absence of the K5X mutation and the 46_72 deletion in Tunisian patients affected with RA, SS and SLE and healthy subjects, and, on the other hand, the absence of association between the R2S polymorphism and the genetic susceptibility of RA, SS and SLE.